When goods are delivered to the buyer on approval or on 'sale or return' or other similar terms the property [ownership] therein passes to the buyer- (a) when he signifies his approval or acceptance to the seller or does any other act adopting the transaction;
(b) if he does not signify his approval or acceptance to the seller, but retains the goods without giving notice of rejection, then if a time has been fixed for the return of the goods on the expiration of such time and if no time has been fixed on the expiration of a reasonable time. What is a reasonable time is a question of fact.
An example of this situation would be if Albert agreed to buy 10 ovens from an overseas supplier on a 'sale or return' basis, so that he can inspect them to decide if they suit his requirements before being bound by the sale.
In these circumstances, ownership of the ovens would pass to Albert only when he signals his acceptance of them, or fails to reject them within a reasonable time.